Method and means for drafting furnaces



Jan. 13, 1931. J. REID METHOD AND MEANS FOR DRAFTING FURNACES Fild March 19. 1927 4 Sheets-Sheet 1 INVENTOR- John. Reid MQM A TTORNE Y8 Jan. 13, 1931-. J, RE|D 1,788,888

METHOD ANb MEANS FOR DRAFTING FURNACES Filed March 19. 1927 4 Sheets-Sheet 2 John, Reid Jan. 13, 1931. J. REID METHOD AND MEANS FOR DRAFTING FURNACES Filed March 19. 1927 4 Sheets-Sheet 5 INVENTOR. 1/0/2778 Rel my M28 M A TTORNEYS Jan. 13, 1931. 1.1mm 1 1,788,888

METHOD AND MEANS FOR DRAFTING FURNACES Filed March 19. 1927 4 Sheets-Sheet 4 \QJ/"MQ/ 111 Patented Jan. 13, 1931 I Iona 1mm QEQNEW mm. 1y. 1 '1 This invention relates to' furnaces, and: more particularly to boiler-furnace draftingsystems; p I It aims to provide an improved method andineans'for supplying and distributively delivering drafting: air to furnace fires ade qua-ts volumeand under conditions of undisturbed flow calculated toprod uce the most effective and economic'results'in the use of fuel. The invention is herein described with I reference to boiler-furnaces ofv ships wherein draftingsystems are required for maintain- 'ing the fires ofa battery of furnaces-insimultaneous operation, and'where only a limlted volume of air is usually available for the punpose.

an eflicient air supply under the variable running' conditions likely to. be experiencedin operation and to insure thesupply, distribution and delivery of air through a closed fan-J draft system under conditionsof stream-line flowf advantageously eliminating fractious turbulences and back-pressures which cause the delivery to be uncertain and spasmodic at one or morefurnaces in a battery, and in; general to facilitate the. 21-11? movement atall points in the system so, as 'to make the distribu-tion substantially equal, and most effective at the furnaces. i

Another object is to deliver a sufilcient airvolume to each of the furnace fires at a nnn1-.

mized speed below the critical speed, of air delivery, that is, at the lowest possible speed promoting efiicient operations which in the majority of Vessels approximates ten feet per second at the furnace fronts. Air delivery to the furnace fires above the stated speed is liable to be spasmodic and uncertain, especial ly-in drafting systems of faulty design herein resistances to air flow therethrough give rise to congestion and fractious turbulences in fan pressures.

passage, causing pulsative or sporadiodi'scharge at the fires, any force of disturbance in air flow being greatly magnified by strong With a draft system embodying appropris atemeans for effecting the delivery of'alr to the furn'acefires in smooth 'and undisturbed An object of the invention is to maintain fires depends upon the f' 'i ce of flow-according to this invention, theengineer incharge can'easilyregulate theair-dist-ribuf tion Without specialfadjustment at any one; fire or boiler sofla's' to cause-all-fires to react correspondingly upon any change of fan pressure, thereby'rlevelopin'g and maintairif ing' thesame'to best'fadvantage underrunning conditions Y Before describing the I invention further, the faultsof construction and practices in operation of-"draftingsystems now in use willobe 'stated sufficiently-to a-iforda clear f understandingand appreciation of the d' istinctions injstr-uctural 'fea-turesand practice Y claimedfor said inve systemsand-practices.

- Inmost'vessels,drafting air for the fires; of a battery of boilerfurnaces, is-distributively delivered thereto" through conveyor" trunks'under'pressurefrom a fan in the enover different parts-ofthe engine equipment Without particular regard for effi'ciency. Theyare;designed 'flapparently on thetheory that 'it makes little difference how'they are erg ranged solong a'sair passage is clear; How- 0 ever, the factis' thatf so many bends in the trunks, especially abrupt'ones, form barriers or obstacles offering resistance to air flow, causing "congestion" an d' violeiit turbulences resula ing i n' pulsative and spasmodic delivery to'the fires unless'provi'sion Tis'made to insure smooth andund-isturbed air flow therearoundu When airis forced" u'nderhighf or increased pressures through-such -faultytrunks,the violence of turbulences pulsations and-static resis'tance-sto a ir-flowthe "'1 increase to such" d'egreefihatthe condition we chaotic'and' it becomes impossible ni'a'intain; efiicient V fires.

Very-little thought s'eemflsflfto Thaw; been given to this vastly, important subject by ship builders and engineers generally, tli'e' prevailing'i'mpression being-that rheuiiveryof iade- I quate volumes offdra-fti air '0 the furnace ntion overthe prior art fan pressure through the conveyor trunks. Following the prevailing theory in operatlon, whenfone of the furnace fires appears to be rece ving an improper supply of air, the marine engineer endeavors to correct the conditionby speeding up the draft fan to increase the force of delivery, thereby making the condition Worse, for while. his actionfmay temporarily improve the firing condition of one boiler, it will almost invariably impair the firing condition of several other boilersin' the battery.

Other faults of construction reside in the branching of the air trunks at pointswhere dlvisions of the air stream are desired; Such moving through a conveyor trunk is of subfaulty constructions are apparently the result of an erroneous theory that a volume of-air.

stantially uniform density occupying the full area ofthe trunk and that the desired provportional divisions of the air stream or .vol-

- 7 half, and where a division inthree equal pro portions is desired, the area of the trunk is divided or branched in thirds, etc. However,

experiments have shown that a volume-of air flowing through a bending trunkdoes notremain of uniform density, nor will it occupy the full area of the trunk either around or,

between bends, unless means is provided for effecting a stream. line flow therethrough. Consequently, in themajority of vessels having drafting systems installed. and operated according to general practice,the desired proportional vdivisions of air supply there-- through are not obtained, which accounts for much inefficient anduneconomic boiler opera tion.v It is an object of thi-s'invention insofar as possible, to cause the movingair vol-- n ne to occupythe fullarea 'of the trunks aroundand between bends and at all points therein. V r

A problem always confronting the marine engineer. isthat ofgetting an adequate supply of air intothe stoke-hold or engine room where the draft-fan is located. As generally known. air-must be scooped up and directed below decks by ventilators and oftentimes- "there is insufficientairavailable at the draftfanto supply the furnacesat the rate the fan isrun, so that. it begins to suck or act in partial vacuunr; Under such conditions the air supply becomes inefficient and thevolume of flow through the trunks to the furnaces obviously'cannot be increased by speedingv up the fan, but this; nevertheless is what is-usually done-by marine engineers believing the air supply; through the; trunks is dependent wholly upon the force of air pressure from the fan. This practice, combined with faulty constructions tendingtocreate disturbances from consumed-fuel through the funnel or stack. The ofl-draft fiues built to converge from a battery of boiler-furnaces to the base of .oneor more funnels, are generally cons'tructedl without particular regard for the way in which the gases may most freelypass therethrough, and much .ineflicient operation is in part occasioned by faulty design inthe offdraftflues. l s V V The purpose of this invention is to remedy the faulty constructions and practices in operation of drafting systems now in use, by providing an improved method and means for drafting the furnace fires on an entirely different principle. l The invention will be best understood by reference to the accompanyingdrawings illustrating one embodiment of a system for v supplying and distributing drafting air to the fires ofboiler-furnaces according to the improved method or principle embodying this invention. i

In said dawings: .Fig. 11 is a somewhat diagrammatic representation ofthe boiler room of a vessel on the line. of; a longitudinal section therethrough, showingthe boilers and associated drafting system with fan and off-draft fines; Fig. 2 is a plan view of a-battery ofboilers with parts of the air draft system shown in sections, 1

Fig. 8 is a side elevation in representation of one of the boilers, with a portion of the main trunk of the drafting system shown in longitudinal section; Fig. 4: is an elevation partly in section taken transversely of the vessel through the boiler room; and 1 Fig. 5 is a sectional side elevation of one of the boilers.

The illustrative system is shown applied to a plurality or battery of ship boiler-furnaces 6, which in this instance are of the oil burning type having three burner openings. Said furnaces are connected by suitable up'-[ takes with a smoke-stack or funnel 7 and air to the boiler-room is supplied through venno source of air supply exceptythat;availablethleikinetic@energylotair-in momentum is un- I desirably converted into static energy or i n the ngine-B om, '01 compartment. in wh ch. it sca ed As air must be; directed. i to said room or compartment by ventilators which are generally Einadequate for; the

Pu pose, the tan, is us a ly per ed. under conditions 7 of l m ted Qrnsutficient airsup 1 ply, Fans of large size and capacity" have 7"eyes of the fan atopposite-sides thereof gen rallye n employed for the-"pu po e, and according: to prior art practiceare driven.

at high speed in orderto force available air under high; pressure" through the system to the fires, as it is generally believed that the requisite suppl-yof air to thejfires denpends upon the pressure from the. fan. The; 7 fans ot'large size drivenat high speed reg- 7 quire considerable steampowerin operation such fans are. not nfrequently driven at excessive rates causing heavy vibration ottentimes resulting in. damage; Further-'1- more, high-speed tan: operation invariably Creates high staticv pressures and resistances to air flow through; the distributive system, with resultant chaoticconditions 0t air delivery and ineflicient operation of the ,fur-

naoes i In the present instance, aspecial ventilag' tor 10 is; provided for supplying air direct to the fan, the lower end of said ventilator being shown with branched sections- 10 hav i-ng bell-mouthed ends discharging into the in order that there maybe-a plenum of air at all times available to the :fan., lhe draft: 1' H 'bend andis smoothly deflected therea-round,

tanj9 ofthe illustrative-system is preferably 'of relatively small size and according tothis.

invention is operated at very'low speed'requiring negligible steam power in operation In fact, the preferred speed of fan QPQIZLlJlOIL isso low incomparison with prior art practice that in several vessels in which the invention has been applied, .it has beenrdiflicult to sufliciently reduce the sp eed'of fan operation. s V, c

Connected with the discharge mouth of the draft-tan 9 is, shown an air conveyor trunk 11 having tributaries .or branchnu'c-ts '1 11 11?, 11 and 11 respectively, through which air suppliedfrom'the fan is distributively delivered toithe plurality offurnaces 6.

The Walls, of such trunks ofierl resistance to free airflow around bending points therein, espec1ally toa1fr moving under high pressure impulse, thereby causing the formation of eddies and static disturbances givingrise to pulsations in the system and resulting inuncertain and spasmodic delivery at the furnace fires. Thus, in prior art systems wherethe trunks are defective for the reasons'stated,

the system. Any increase oi fan. pressure tor the purpose oi? driving-the air through thesystem by sheer torcesimply magnifies thedisturbances and-resistances in; air movement through the system, 1

p In order, to overcome these-disturbances, the' kinetic energy ot the airinmomentum thlfqlligh the system should be preservedand 7 according to this invention,-means are-pro videdior effecting a streamline-flow of the" airaround the bends and at all po i-nts in the trunlr portions of the system.

At the-bend in the conveyor trunkl l abovethe point-where the latter is shownconnecting -with} the evas or discharge I opening: of

the draft-fan casing, a rectifier' 12 is represented; comprising a spaced; series of radially disposed arcuate 012 curved guide-vanes or sweeps earned between arm -portions: of a 1 movable; irame.v Said rectifier is provided with means for adjustment exteriorly of; the trunkto position causing air under momentum; impulse from the fan to flow in directed stream-line movement around the bend. As; limited portions or the air may pass between the spaced vanes of the rectifier, the total volume is substantially uniformly distributed throughout the full area of the trunk ment is preserved. v

Where other bends in the trunks occur,

correctors13 similar to or corresponding; with the .rectifier 712 are advantageously placed In theillustratiyesystem, a corposed spaced series of curved vanes or sweeps angularly adjustable by means of a manually movable rod 13 to position causing the undisturbed and stream-line flow of air around the bend in which it is located.

pression occur-in the trunks, corrector devices similar to the corrector 13 are advantageously placed. At such a point-in the I H v The vanes of the corrector act similarly to the vanes of rector-Bis shown comprising a radially dismain, trunk portion, a corrector device 14 is shown; comprising a shutter-like arrangement of guide-vanes adjustable similarly to the; corrector 13 to; angular position causing the, undisturbed. deflection and stream-line flow of vairin proper direction and uniformoccupationfoi, the trunk area. Such a device tends .toiurther preserve the kinetic characteristic of air movement through trunks e a r 5 1 Where gradual bends occur in the trunks,

it is desirable to place a slightly "curved plate 15' conforming substantially to the angular trend of thetrunk so as tocause' substantial proportions of the flowing air volume to pass along opposite sides thereof and aid its directional "movement through the trunk.

As air has a tendency to flow in somewhat greater density in thecenter of the trunksandthere is more or less friction along the walls thereof,'it;is advantageous to arrange spreading-or distributive elements at'difierexit points in straight sections'of the trunks. lnastraight section of the main trunk, a distributive element 161s showncomprlsing a honeycomb arrangement of thin vertical and horizontal plates orvanes between which limited portions of air volume may pass, so thatgthe total volume of air in (movement through the trunk is caused to spread out and occupy substantially the full area' of the trunk in flowing through said element;

In the illustrative system, the rectifier,corrector and distributive elementsare shown in close proximity, each comprising in one form or another, an {arrangement of guide vanes of curvature or alinement conforming substantially to the directional trend ofthe trunk and the proper line of air movement therethrough. In installing or reconstructing a system, these director elementswould not probably be arranged in suchclos'eproximity, but are so represented for purposes of illustration in a comparatively short trunk body. In practice it may be advantageous to usesuch elements not only atapprop riate points in'the ,main Strunk body, but also" at points in the tributary trunks or ducts leading to the individual furnace fires. The

employment of said elements or their equivalents at points in the tributary'trunks is contemplated as working requirements or corrective measures may suggest.

Vhere branching of the conveyor trunks is desired for effecting a proportional division of the air supply volume in diverging directions for delivery in corresponding amounts to a plurality of furnaces, the prior art practice is to branch the trunks on divisional lines directly proportional to the does not ordinarily move through the con-v veyor trunks with uniform density throughout the trunk area,'e ven thoughmeans may be provided for efiectinga stream-line flow therethrough and the expected divisions of air" volume rarely result, sothat the iamounts delivered-to the furnace fires have not heretofo're been substantially equalized either in volume'or rate of flow. 1

Inforderto effect the desired division of air volume at branchingpoints in the trunks, swinging flaps or gates 17 ar'eshown manual ly adjustable "exiteriorly'liof the" trunks 1 tot branch-trunk openings and increasing or decreasing the amount of air volume flowingthereinto,' so that the proportionsof air supply flowing into" the branch or tributary trunks may-be equalized or regulated as desired? By suchme'ans theengineeris enabled to control the air divisions into the tributary trunks according to working requirements.-

When the gates of a system embodying this imenaoahavsonce been adjustedto appropriate position? no further adjustment will ordinarily be' found necessary and" all the fires will-respond correspondingly upon any change of-fan'pressure; Where a division of the air volume flow ing through one of the branch or tributary trunks is desired, as for instancein the branch 11 of theillustrative system, a similar'gate 18 should be provided for a like purpose.

At bendingpoints in the branch or tributary trunks, director vanes or sweeps'l9 corresponding1n;forrn and purpose to the corjrector vanes 13, are advantageously pro-- vided in "order t'o'feifect a stream-line flow of the airtherearound and preserve the ki- ,netic characteristic of the air movement If the tributary trunks are of sufficient size to permit it, rectifier or corrector elements corresponding with the elements 12-and 13 may'be'employed as hereinb'efore stated.

' At points where the tributary trunks or" ducts deliver air to the furnace fronts or; air-heaters thereof, the usualprior art prac-' tice is to extend'a curved plate or scoop partly into the trunk forcatching or deflecting a portion of the air volume fiowing'therethrough and directing it into the furnace'or heater. Such scoops are alone'inadequate for the purpose as'they do not ordinarily catch ordeflect the required air volume for delivery to the furnace fires, nor dosthey se regate or trap at the respectige fu1naces,;

aproper proportion of the air volume flowing through the trunk to adjacent furnaces so as substantially to equalizethe air volume delivery at :all furnaces. This is especially true in systems of faulty design where the air movement throughthe trunks is unduly turbulent and spasmodic. Under such con ditions the respective fires will not be correspondingly responsivetojchanges in fan pressure, so that inefficient operation of one furnace cannot be corrected by Varying the I speed of fanoperation, without injuriously affecting the operation ofother furnaces. I In the illustrative system, the tributary trunks or ducts deliver air toair-heatersQO of the furnaces through central open ngs.

therein. The air-heater spaces are shown divided by diaphragm plates'21 having curved portions 21? extending into :the trunks providing fpickups for catching av suflicient portion of the air volume-movingtherethrough and directing the samc intoi'one side i of the air-heater. These extensions of the diaphragmplates are of a length'calculated to trap and cause equal proportionsor vol 'umes of. air to enter the heaters at each fur nace. To assure equalized delivery at all furnaces small adyastable flaps or gates corresponding with the gates 17 mayadvan tageously be provided on the ends of each" diaphragm plate. At the concave'sidesof the ri'chup portions of .the diaphragm plates, the walls of the tributary trunks are shown with curved portions 22having edges registering with the heater opening and conforming substantially with the pickup curvature so as to cause an undisturbedand stream-line flow of the air into that-part of the air-heater opening on. what may be called the windward side thereof theair entering at such point being given a partial rotation aiding its turn around 180degrees in passage through and down that side of the heater. Opposite the air-heater opening's the outer wallsof the tributary trunks are shown with outwardly extending curves 23 f larger arc, conforming substantially wit-h'the curvature of the pickup 'portions of the diaphragm plates andprovi'ding en iargements in thetrunk bodies enabling the remaining or unscooped proportions of :air

tion with the amount'entering'at the wind.-

wardside thereof. However, where the trunk extends from one" furnace to another a complementary pick-up for the heater opening of the preceding furnace is: pro};

vided, which in the form shown comprises,

a curved scoop-plate; 24 registering with the ,leeward; side of: said opening behind the" ma.in pichup"" portion-21*? of the diaphra'gm plate and conforming substantially ftoJthe curvature of the latterr The complementary pickup causes the required v-olum'e'of air to enter smoot-hlyat the leeward side oft-he heater opening and yet allows the necessary air volume to pass therearou'ndto the adja- Y Where the tributary trunk termi" 'centfurnace; Itmay also'be advantageous to provide an adjustable I gate on the end thereof similar to the gates 17hereinbe fore 7 described. 5

' Aflsystem control-means forth'efair' According to' this nventiom the draft f-an Q'is' driven at'the lowest permissible speed in order to minimize thearr pressures' 1n the conveyor trunks andto mf nlmize the excess 7 ofair delivery'iat" the-furnaces." The fan embodying trunk portions .of

' stream-line construction withmeans foreffec'ting the undisturbed flow of air there-' through under momentum impulse from the draft-fan is't-hu's' provided together with flow power and driving speed {required for deliv V Y ering and distributing adequate volumes of airto the several furnace fires will be; limited to that suflicient merely to create the necessary velocity of air movement at a-jmodified 0nd at tliefu rnacef-ronts'. A slow speedrorate notgen'era'lly exceeding ten feet per sec- I tation of the draft-fan would in itself tend to reduce air pressures and violence- 0f turbue lences in a system of faulty construction, but

a: system of stream-line construction embodying means for effecting :a'n undisturbed flow of airtherethrough accordrn to this invention, 'will virtuallyrelinnnateractious'turbw lences and static air-pressures, eventhough the speed of fan ope'rationi'mayibe increased.

, This invention thereforejprovides what may aptly be called a, doub'le-che ik against static pressures for resistances and undesirabletur bulences in air flow through the-conveyor; trunksf I '1 '-1 In joldel to obtainfthe most efiicientand economi'c results in furna'ceoperation, the air delivered thereto'la'ccording to the "method and meanseinbodying this invention should be utilized' 'to the bestadvantage, as it is' not I alonesuffici ent for theair to be {delivered to the furnaces in'undisturbed movement under I modified. pressure. I When asystem embodying this invention is employedjin connection with coal burning furnaces ,thegair is deliv ere'd at the ash-pit'ope'nings,"whilein 'oil'burning-ru aees :iltisidelivered to the airheater spaces thereof as illustratedand hereinbefore described. 1

; :T'he most etlicient and economic utilization of air delivered-to coal burning furnaces may be obtained byjaj circulation th'erethrough' according to "the method and means disclosed 7 in "my 'co pending application Serial Number 122,9d8, filed July :regieeegror improvements in ai'r draft systemsfor furinace'sz Where the inventioniis applied to oil air discharged *into the "air-heater spaces thereof is heated and passesldown delivery p H burn ing" furnaces aslinithe present instance, the f nozzles 25 "onjopposite sides the'reof toward,

the burner openings 26.: At bending points in said delivery nozzles, spaced curved vanes [27- are. shown for guiding a the heated air? in undisturbed flow therearound toward .the burner openings aroundf 'which it flows in divided currents. Y

'VVith defective air delivery systems operated 'accordingtoprioi' artpractice, it has f-been idifiiculta if not impossible to; obtain the ideal flame condition. because of the 1 pulsalatent; combustion toWard the back of the furnace,-'which is most undesirable'and inefficient. Vhcn pulsative and spasmodic deliVeryat the-burner openings is coincident with high fan pressure,- theflame cannot be maintained constant and the cond1t1on 1s made-considerably worse. Following outthe hereinbefore describedprinciples of directed stream-lineflow through the system, curved guide-vanes 28 and 29 are shown-in'inverted V aI 'rangeIne1'1tbe1ow the burner openings for causing aregulated. conjunctions. of air currents frornaround said openings-and di noting. the air with-a moderated rotary or swirlingm'iovement into the annular spaces surrounding the ,usual cone-deflectors 30 so as to envelope the oil coneifroln the. burner nozzles, withresultant early combustion at the fronts of the furnacesi- Said vanes so arranged control-the air movement to prevent -undue; agitation vin-passage through the burner openings so thatthe eflicien'cy, of. air delivery'will not be impaired at such points where a moderated turbulence of. aswirling character as distinguished from fractious turbulence of air movement is expresslyfldesirable. 3 Thebest resultswill follow from 'a concentrated spiral flow of the air-downwardly under the flame to counteract the tendency of the mistedoil cone to throw'its heavier I globulestoward the bottomof the-furnaces;

5, which: is the ideal condition, since the atomized oil is completely combusted before reaching the back ofthe furnace and the flameis supported below the boiler area between'the moderate air pressure at the front of the furnace and the suction of the ofi-draft at they back thereofwFors efficient combus tion, it is important that the-volume and rate of'air'flow into thejfurnaces behind-the flames should be sufiicient to 'justioil crcome thetencb ency of the-fires to backfire or throw back into the furnace fronts underia m nimumdellvery of excess-air In other Words,the"volume and speed of air dehwry to the fires should stack or stacks.

excess of that required'for flame propaga tion. Thatis, since the stack-draft conditions are largely unalterable, the fan-draft should be regulated so as substantiallyto balance the volume and speed of air delivery to the fires-against the forcelof stack suction at each furnace in order to obtain the bestre- Such regulation sults in fuel consumption. causes the fires to burn with an even beat or short periodpulsation, the fires in all furnaces being simultaneously and correspondingly controllable by the fan action.v After the proper ad ustments .have once been made,

. if the fire in; one furnace is properly. drafted, the fires in all the furnaces will be correspondingly drafted and will respond simultaneously to any change of fan action regardless of changes occurring in the furnace draft or stack induction. 7 p

Although the stack draft conditions are largely unalte-rable as above stated, too little attention is oftentimes given to the construction and arrangement of theoftdraft breechings or flues leading from the furnaces to the In the majority of vessels, no provision is made for directing the waste gases or products of combustion in smooth and unretarded. flow through the uptalres. Uptakesor breechings leading to the stacks or funnels should be so designed that the offdraft action therethrough upon the several furnace fires from the stack pull, will be substantially equalized. under changing conditions of Wind. Weatherand temperature, and since stack pull varies withtem'pera ture, atmospheric conditions and wind action across the tops thereof, it is preferable to divide and cap the stacks so as to equalize their action to the breechings.

Eflicient results may be obtained by incor porating in the breechings, some of the principles of the air delivery trunks embodying this invention.- In the illustrative system the breechings 31 are shown Withoutwardly extended-curved walls at bending points therein for enlarging the trunk area and permitting free passage of gases therearoundi WVithinthe breechings where the latter connect with the furnace air-heaters, are represented division" plates 32 for. equalizing the stack pull therethrouglrto the furnace fires. spaced guide-vanes33 and 3-l are represented in curvature conformingsubstantially to the directional trend of the trunks for effecting .a stream line flow of the gases therethrough,

similarly-to the rectifier and corrector elements 12 and 13 hereinbeforie'-described.-. Nhere the breech ngs convergingly connect- With the'bottom of the stack 7, EtlllVlSlOIl plate .535 is represented for equalizing the stack pull to-the breechings, said plate'be ing preferably. adjustable for the purpose.

.An ideal drafting system producing effecf-beyminimizedto an'e'xtent. only-slightlyjntual anol economic results in furnace. opera.-

At bending points therein, series of' I tionaccording tothe method embodying'this invention is thus provided. The invention,

' dealing with the delivery aud o-utilization of air from the point of supply from above decks tothe'point of discharge at the funnel top, isapplicable mutatis mut andis to anyclosed draft system for furnaces whether of' sthecoal or oil burn ng type.

In'the case of anew vessehjthe complete system may be installedwith the various fea- -tures :and. factorsicorrelated' toward the high- V estefficiency and economy :in the use of fuel.

In the case ofan' old'vesselin which comrplete replacement may'not be desired, the

The .advantages'of this invention and its improvement over'prior art constructions and practices will be appreciated, especially by ship owners who for many years have been concerned with increasing losses resulting in uneconomic use of fuel from errors in construction, equipment and operation of forced draft systems of the prior art. By applying the improved method and means embodying this invention either to new or old vessels, tremendous saving in fuel and far more eflicient operation will result. The cost of installa tion of the improved system in a new vessel does not exceed that of the normal equipment, while the'cost of correcting the system of an old vessel would not probably exceed I the amount saved in fuel consumption in. a

few months operation. In vessels to which the invention hasbeen applied, savings as high as 15 to 20 percent in fuel consumption have been recorded. The value and importance of the invention in its advance of the art will therefore be obvious.

Since various constructions and arrangements with numerous combinations and sub-' combinations of elements and equivalents 'embodying this invention may be Inade'without I departing from the spirit and scope thereof, it isnot intended that the appended claims shall be limited tothe specific construction and arrangement hereinbeforeillustrated and described. I I I Having thus described my invention, what I claimas new and desire to secure by Letters "Patent of the United States'is 1. The improved method of producing com 'bustion of fuel in 'furnaces'l'ocated withina substantially enclosed space under conditions of limited air supply and forced indirect de livery thereto, which consists in'drawin'g airfrom theouteratmosphere toward a point removed from said enclosed space but also under conditions of limited air supply, supplying such air along; a predetermined path from v said point :to "thefurnaces under continuous" I steady low-pressure impulseinducing gentle momentum :flow, preserving a gentle V and :un'turbulent fiow of the air alongzits said apath of'movemcnt to the furnace'sQand maintaining a continuous andsteady evacuationiofgaseslfrom the furnaces-in substantial balance with the volumeand momentum of theair I I deliverythereto;

2. The improvedmethodofproducingfcom substantially enclosed space "under conditions .bustion-of fuel. in furnaces located within a of 'limited air supply and-forced delivery thereto along a tortuous path, which-consists in drawing air continuously from theoutside atmosphere toward a point outside and remote "fromsald enclosed space, directing such air under continuous and steady. low-pressure o i I impulse from said point along its predeter;

mined path to the furnaces, dividing and distributing the air in substantially equalized proportions to the respective furnaces while preserving.an'undisturbedstream-lineflow 0f the air in its tortuous conduct and distribution thereto, imparting adesirabl'e turbulence'i to. the air at the points of discharge-into the fire chambers of the furnaces,and-maintain- V inga continuous'and steady evacuation of gases from the furnaces in substantial balance "with the volume and'speed of the air delivery thereto. 7.

3. A systein for producing combustion of fuel in plurality of furnaces tlocated withina substantially enclosed space under con ditions of limited air supply and forced de-' livery thereto :along a tortuous path, comprising in combination; conveyor Jt'riunks w having .distributiw e ducts for conducting air to the furnaces from a point outsideuand res I-note from said space 'butalso substantially enclosed under conditions of limited air .sup-

ply, means for drawing air a continuously from-the outer atmosphere toward said polnt,

meansfordirect'i-ng such airinto andthrough said't runks undercontinuous and steadylowpressure impulse-inducing gentle momentum flow thereth-rough, means within said trunks andrducts causingdivisional flow ofjthe air volume-thus suppliedso as to assure distributive delivery to the several furnaces in substantially equalized proportions, ,meansfineluding out-sweeping bend constructions. of

said trunksandductsandthe arrangement of 7 director vanestherein to induce and preserve acontinuo us, stream-line-flowlof the air therethrough to and into the furnaces, 'means'dis' posed in the 'fire-rchambersvof the furnaces for imparting 'afmoderated turbulence to the air at such points of disc'h arge thereinto, and

means ,maintaining a continuous, steady and stream-line evacuation ofgases from the correspondingly responsive to and controliable by the action of-the aforesaid means for directing air through said trunks.

4'. In combination with the air impeller and'conveyor trunks of a closed draft system for. producing combustion of fuel in aphrralityof furnaces located within a substantially enclosed and confined space'under bonditions of limited air supply-and. forced delivery thereto along a tortuouspath from an' other substantiallyenc-losedspace outside'and remote therefrom, the improvement which consists in the provision of means-including out-sweeping bend construetionsi of said trunks and the arrangement of director vanes therein to'induce and maintain i anundisturbed stream-line flow of air therethrough under momentum impulse from the ail-Vimpellei', means includingvanes deposited iii said trunks to effect divisions of the air volume flowing therethrouglr for distributive delivery to the respective furnaces in substantially equalized proportions, means pro vided-by the trunk walls of contour eflfecting a smooth and eddyless delivery of'airl into the respective furnace openings; and means effecting atcontinuous, steady and streamline off-draft of gases from the furnaces in substantial balance with the volume and speed'of the air deliverythereto through the system. y l -1 5. In combination with the air conveyor trunks and draft fan of a closed draft systhe trunks with a constant and onwardly moving stream. p

6. The improvement in conveyor trunks ofa closed draft system including a draftfan for distributively supplying drafting air to a plurality of furnaces located withina.

substantially enclosed space under conditionsof limited air supply and forced delivery thereto alonga tortuouspathfrom an other substantially enclosed space, which consists in forming thetrunks with enlarging outwardly extended? curves in the outer wallsfatv bending,-'divisional and delivery points thereof, arranging guide-vanes with in the trunks fat bending or curving points therein on lines oft-curvature conforming substantially with the directional trend of the trunks, providing flow distributive and directorate vanes'within the trunks at points along JOHN REID.

temfor suppling equal and adequate volumes 1 of air at minimum velocities and'pressures simultaneously to a plurality of furnaces located within a substantially enclosed and airrarified space under conditions of limited air supply and forced delivery theretoalong i101? tuous paths from another substantially en' closed space outside and remote therefrom,

the improvement whi'chconsists in the provision 'of means 1I1Cll1Cl1Ilg director vanes within the trunks at bending, divisional'and straiglit sections thereof effecting a stabilized, stream-line and non-turbulent flow of I to air therethrough under momentum impulse from the fan, means effecting division of the flowingair volumes for distributive delivery to the respective furnaces in substantially equalized proportions, means provided by the trunk walls of contour effecting a smooth and eddyless delivery of the; distributed air volumes into the respective furnacesandmeans for imparting a moderated turbulence;

to theair at points of discharge into the fire chambers of the furnaces, said incoming air to the trunks always following in the 'wake (if-the funnel Qif d a t andmmp t y fill g- 

